Sparse channel estimation for cooperative underwater communications: A structured multichannel approach

This paper examines structured methods to perform multichannel estimation for underwater acoustic communication networks. Much of the receiver/protocol design for cooperative communications requires channel state information at the receiver. The proposed multichannel estimation algorithm exploits relationships between the multipath channels of cooperating transmitting nodes to a destination node. A simplified channel model is proposed from a geometry-based ray-tracing model. From an approximation of the channels between the relays and the destination, an iterative scheme is derived. The proposed method exploits the sparse nature of underwater acoustic channels and in so doing improves performance over unstructured methods. The efficacy of the proposed method is evaluated via simulations, i.e. comparing the mean-square error of the estimated channel with its Cramer-Rao bound.